Protection of digital content (such as audio and video) transferred between computers or computing devices over a network (such as the Internet) is fundamentally important for many enterprises today. Enterprises attempt to secure this protection by implementing some form of Digital Rights Management (DRM) process. The DRM process often involves encrypting the piece of content (e.g., encrypting the binary form of the content) thereby to restrict usage to those who have been granted a right to the content. Typically the encryption is provided at a central server and the content distributed to client devices.
Some of the rights to pieces of content that are distributed by existing DRM systems are permitted to be viewed on a certain number of distinct devices (i.e. platforms such as computers, computing devices, players, cell phones) simultaneously. For instance, one existing DRM system distributes certain recorded songs to both desktop computer systems and portable player devices using the same method. The method used does not take advantage of the increased performance of the desktop system to increase DRM protection. If the DRM encryption is broken for one of the two platforms, it can be used to break the DRM encryption on the other platform and on other instances of the same platform. Existing DRM systems thereby typically widely distribute content protected by only one digital rights protection mechanism. However, content providers would like to have their content viewed on different platforms and would like to maintain the integrity of the security measures while taking advantage of the differences in resources on the various recipient platforms.
However, the present inventors have recognized that existing DRM systems often do not allow the mechanism for decryption of protected content to vary based on the specific recipient device and device type. Allowing the authentication or verification (such as an HMAC or digest) to vary across devices and device types prevents a party that breaks the DRM security on one device or device type to break the DRM security on another device or device type. Furthermore, allowing different mechanisms for authentication to be used for different device types can allow the distributing party to choose use a mechanism more suited to the target device. Therefore the present inventors have identified a need for a DRM system that flexibly allows content distributors to set content protection mechanisms based on both the device and the device type.